Re: Returning a ellipses

[HyperHacker <hyperhacker@...>]

On Thu, Dec 8, 2011 at 20:55, PROXiCiDE <saiyuk7@gmail.com> wrote:
> HyperHacker <hyperhacker <at> gmail.com> writes:
>
>>
>> On Thu, Dec 8, 2011 at 20:37, PROXiCiDE <saiyuk7 <at> gmail.com> wrote:
>> > Xavier Wang <weasley.wx <at> gmail.com> writes:
>> >
>> >>
>> >> Maybe you can do something like this:
>> >>
>> >> function Test(s, a, ...)
>> >>   -- do something to calculate the first field
>> >>   local ret = --....
>> >>   return ret, Test(s, ...)
>> >> end
>> >>
>> >> ---------- Forwarded message ----------
>> >> From: PROXiCiDE <saiyuk7 <at> gmail.com>
>> >> Date: 2011/12/9
>> >> Subject: Returning a ellipses
>> >> To: lua-l <at> lists.lua.org
>> >>
>> >> I want to pass a function that supports
>> >> ellipses "..." and return several of
>> >> them into different variables..
>> >>
>> >> example
>> >>
>> >> function Test(...)
>> >> end
>> >>
>> >> a,b,c,d,e = Test(1,2,3,4,5)
>> >>
>> >> Reason for this being, i want to be able to
>> >> read a structured data into variables...
>> >>
>> >> example reason
>> >>
>> >> magic,version, headersize,directorycount,directorylocation =
>> >> ReadDirectory(f,"s",16,32,32,32)
>> >>
>> >> S = obviously a String
>> >> 16 = Int16
>> >> 32 = Int32
>> >>
>> >> I would actually parse the the ellipses using the
>> >> "var = select(i,...)" from a "for" statement
>> >>
>> >> But what i cant understand is how do i seperate
>> >> these into different variables
>> >> that are returned
>> >>
>> >>
>> >
>> >
>> > Well Test will be reading data from a binary file
>> > into these specific variables, the ellipses
>> > would hold the size of the data to be read from the file
>> >
>> > example
>> >
>> > function Test(f,...)
>> >  for i=1,select("#",...) do
>> >  local v = select(i,...)
>> >  if (type(v) == "number") then
>> >  store_var = FileReadSize(f,v)
>> >  end
>> >  return -- Store Variables here
>> > end
>> >
>> > a,b,c = Test(f,32,16,32)
>> >
>> >
>> >
>>
>> So you want to store your return values in a table, and unpack them at the end.
>> function Test(f,...)
>>  local ret = {}
>>  for i=1,select("#",...) do
>>  local v = select(i,...)
>>  if (type(v) == "number") then
>>  ret[#ret+1] = FileReadSize(f,v)
>>  end
>>  return unpack(ret)
>> end
>>
>
>
> thank you very much this indeed worked, i wish there was
> a simplier way, in C you could read a file structure with
> fread function
>
> sorry to trouble you, would there be a way to simplify this?
> like
>
> array = Test({magic=16,header=32,version=32})
> array.magic
> array.header
> array.version
>
> created from reading the file contents? ive tried
>
> function Test(arg)
>  local t={}
>  for k,v in pairs(arg) do
>  t[v] = FileReadSize(f,v)
>  end
>  return t
> end
>
> but the ordered of how the structured was made is
> sorted in a different way and it becomes unorganized..
>
> example.. array.magic does not read it in the correct
> order as it was created in the index of the argument
> passed in the function
>
> instead array.magic becomes array.header
>
>

Ordering of table keys isn't guaranteed in Lua. You'd need to do something like:
struct = {
{'magic', 16},
{'header', 32},
{'version', 32},
}

-- 
Sent from my toaster.